[Tacrolimus Induces Pain by Upregulating the Synaptic Expression of AMPA Receptors in the Spinal Cord Dorsal Horn]. / ä»–å ‹èŽ«å¸é€šè¿‡ä¸Šè°ƒè„Šé«“èƒŒè§’AMPA受体的突触表达诱发疼痛.

Objective: To investigate the effects of long-term administration of tacrolimus (also known as FK506) on the pain-related behaviors in mice and to study the underlying mechanism of pain induced by FK506 via measuring the effect of FK506 on the synaptic expression and phosphorylation of alpha-amino-3-hyroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor in the spinal cord dorsal horn of mice. Methods: 1) A total of 24 mice were evenly and randomly assigned to two groups, a FK506 group and a Saline group. The FK506 group was given daily intraperitoneal injection of FK506 and the Saline group received normal saline. Both groups received injection once a day for 7 days in a row. Some of the mice ( n=6 in each group) were monitored for the changes in the paw withdrawal threshold (PWT), the paw withdrawal latency (PWL), and the spontaneous pain behaviors to establish the pain model. The other mice ( n=6 in each group) of each group underwent isolation of the dorsal horn when obvious pain symptoms were induced on day 7 of injection. Then, immunoblotting was performed to determine the synaptic expression and phosphorylation levels of GluA1 and GluA2 subunits of AMPA receptors. 2) The mice were randomly divided into two groups, FK506+calcineurin (CaN) group and FK506+Saline group ( n=6 in each group). After the pain model was constructed, the mice were given intrathecal injection of recombinant CaN (also know as 33 U) or normal saline. Then, 60 minutes later, the PWT and the PWL of the mice were measured to investigate the role of CaN in FK506-induced pain. 3) Another18 mice were selected. The mice were randomly and evenly assigned to three groups, a control group (receiving intraperitoneal injection of normal saline followed by intrathecal injection of normal saline), FK506+Saline group (receiving intraperitoneal injection of FK506 followed by intrathecal injection of normal saline) and FK506+CaN group (receiving intraperitoneal injection of FK506 followed by intrathecal injection of CaN). Then, 60 minutes later, the spinal cords were isolated and subjected to immunoblotting assay to determine the role of CaN in FK506-induced AMPA receptor modification. Results: 1) After 7 consecutive days of intraperitoneal injection of FK506, the PWT and PWL of mice dropped significantly, reaching on day 7 as low as 22.3%±0.05% and 66.6%±0.05% of the control group, respectively ( P<0.01). The FK506-treated mice displayed evident spontaneous pain behavior, presenting significantly increased licking activities ( P<0.01). These results indicated that FK506-induced pain model was successfully established. Immunoblotting assay showed that the total expressions of GluA1 and GluA2 subunits in the spinal dorsal horn of the FK506 group remained unchanged in comparison with those of the Saline group. However, FK506 specifically induced an increase in the synaptic expression of GluA1. In addition, the phosphorylation levels of GluA1 at Ser845 and Ser831 in FK506-treated mice were significantly increased in comparison with those of the control group ( P<0.05). 2) Compared with those of the mice in the FK506+Saline group, the PWT and the PWL of mice in the FK506+CaN group were significantly increased ( P<0.05). 3) Compared with those of the FK506+Saline group, the synaptic expression of GluA1 were decreased in FK506+CaN group ( P<0.01) and the phosphorylation levels of GluA1 at Ser845 and Ser831 were significantly downregulated ( P<0.001). Conclusion: The hyper-expression and hyperphosphorylation of GluA1 subunit in the spinal cord dorsal horn resulting from CaN inhibition contributes to the FK506-induced pain syndrome. FK506 induces the synaptic hyper-expression and hyperphosphorylation of GluA1 in the dorsal horn of the spinal cord through CaN inhibition, thereby inducing pain.

GPR39 regulated spinal glycinergic inhibition and mechanical inflammatory pain.

G protein-coupled receptor 39 (GPR39) senses the change of extracellular divalent zinc ion and signals through multiple G proteins to a broad spectrum of downstream effectors. Here, we found that GPR39 was prevalent at inhibitory synapses of spinal cord somatostatin-positive (SOM+) interneurons, a mechanosensitive subpopulation that is critical for the conveyance of mechanical pain. GPR39 complexed specifically with inhibitory glycine receptors (GlyRs) and helped maintain glycinergic transmission in a manner independent of G protein signalings. Targeted knockdown of GPR39 in SOM+ interneurons reduced the glycinergic inhibition and facilitated the excitatory output from SOM+ interneurons to spinoparabrachial neurons that engaged superspinal neural circuits encoding both the sensory discriminative and affective motivational domains of pain experience. Our data showed that pharmacological activation of GPR39 or augmenting GPR39 interaction with GlyRs at the spinal level effectively alleviated the sensory and affective pain induced by complete Freund's adjuvant and implicated GPR39 as a promising therapeutic target for the treatment of inflammatory mechanical pain.

Reduced expression of APLP2 in spinal GABAergic inhibitory neurons contributed to nerve injury-induced microglial activation and pain sensitization.

The amyloid precursor protein (APP) is critical for the pathogenesis of Alzheimer's disease (AD). The AD patients usually have lower pain sensitivity in addition to cognitive impairments. However, considerably less is known as yet about the role of APP and its two mammalian homologues, amyloid precursor-like protein 1 and 2 (APLP1, APLP2), in spinal processing of nociceptive information. Here we found that all APP family members were present in spinal cord dorsal horn of adult male C57BL/6J mice. Peripheral nerve injury specifically reduced the expression of spinal APLP2 that correlated with neuropathic mechanical allodynia. The loss of APLP2 was confined to inhibitory GABAergic interneurons. Targeted knockdown of APLP2 in GABAergic interneurons of GAD2-Cre mice evoked pain hypersensitivity by means of microglia activation. Our data showed that GABAergic terminals expressed APLP2, a putative cell adhesion protein that interacted with microglia-specific integrin molecule CD11b. Knocking down APLP2 in GAD2-positive neurons to disrupt the trans-cellular interaction led to microglia-dependent pain sensitization. Our data thus revealed an important role of APLP2 for GABAergic interneurons to control microglial activity and pain sensitivity.

Characterization and Antibacterial Activity of a Polysaccharide Produced From Sugarcane Molasses by Chaetomium globosum CGMCC 6882.

As a by-product of the sugar industry containing many sugars, proteins, nitrogenous materials, and heavy metals, molasses is rarely used for polysaccharide production. In the present work, a Chaetomium globosum CGMCC 6882 polysaccharide was produced from sugarcane molasses (CGP-SM) was successfully produced from sugarcane molasses. The yield of CGP-SM was 5.83 ± 0.09 g/l and its protein content was 2.41 ± 0.12% (w/w). Structural analysis showed that CGP-SM was a crystalline and amorphous polysaccharide containing rhamnose, glucosamine, galactose, glucose, mannose, fructose, and glucuronic acid in the molar ratio of 10.31: 1.14: 2.07: 59.55: 42.65: 1.92: 9.63. Meanwhile, weight-average molecular weight (Mw), number-average molecular weight (Mn), and polydispersity (Mw/Mn) of CGP-SM were 28.37 KDa, 23.66 KDa, and 1.199, respectively. Furthermore, the bacteriostatic assay indicated that CGP-SM inhibited the growth of Escherichia coli and Staphylococcus aureus in a concentration-dependent manner, and its inhibitory effect on S. aureus was higher than that of E. coli. Above all, this work provides a green method for the production of bioactive polysaccharide from sugarcane molasses.

Taurine Supplementation Lowers Blood Pressure and Improves Vascular Function in Prehypertension: Randomized, Double-Blind, Placebo-Controlled Study.

Taurine, the most abundant, semiessential, sulfur-containing amino acid, is well known to lower blood pressure (BP) in hypertensive animal models. However, no rigorous clinical trial has validated whether this beneficial effect of taurine occurs in human hypertension or prehypertension, a key stage in the development of hypertension. In this randomized, double-blind, placebo-controlled study, we assessed the effects of taurine intervention on BP and vascular function in prehypertension. We randomly assigned 120 eligible prehypertensive individuals to receive either taurine supplementation (1.6 g per day) or a placebo for 12 weeks. Taurine supplementation significantly decreased the clinic and 24-hour ambulatory BPs, especially in those with high-normal BP. Mean clinic systolic BP reduction for taurine/placebo was 7.2/2.6 mm Hg, and diastolic BP was 4.7/1.3 mm Hg. Mean ambulatory systolic BP reduction for taurine/placebo was 3.8/0.3 mm Hg, and diastolic BP was 3.5/0.6 mm Hg. In addition, taurine supplementation significantly improved endothelium-dependent and endothelium-independent vasodilation and increased plasma H2S and taurine concentrations. Furthermore, changes in BP were negatively correlated with both the plasma H2S and taurine levels in taurine-treated prehypertensive individuals. To further elucidate the hypotensive mechanism, experimental studies were performed both in vivo and in vitro. The results showed that taurine treatment upregulated the expression of hydrogen sulfide-synthesizing enzymes and reduced agonist-induced vascular reactivity through the inhibition of transient receptor potential channel subtype 3-mediated calcium influx in human and mouse mesenteric arteries. In conclusion, the antihypertensive effect of chronic taurine supplementation shows promise in the treatment of prehypertension through improvement of vascular function.